Welcome to the Winobloggers webpage! Students and professors from different universities meet to discuss their findings on Winogradsky columns they constructed!
We learn how to formulate hypotheses, observe, comment, ask and reply to questions related to our scientific experiments.

Winogradksy columns

'In the field of observation, chance only favors the prepared mind' Pasteur 1854

Blog posts

Monday, 16 March 2015

Cadiz, 9B: Winogradsky column, first week.

Hi, everyone! We are three students from UCA

The sources of the mud that we used are
the river and the beach, salt water was
added to the mixture. We've mixed the mud with paper, calcium carbonate ,
ferrous sulfate and calcium sulfate.

The paper was added to the mixture due
to the fact that it provides a source of carbon(cellulose), the calcium
carbonate was used because it produces carbon dioxide, another source of
carbon. Ferrous sulfate and calcium sulfate were used as a source of sulphur.

The Winogradsky column was made on Tuesday
3rd march 2015.

The mud was mixed with the carbon
and sulphur sources in a bucket, then, it was added to the bottle and packed in
the bottom. More mud was added to fill two thirds of the bottle capacity. Then the
salt water was added to the bottle.

The column has been placed next to a
window.

The added material triggered
microbial activity that depletes the oxygen in the mud, creating an oxygen
gradient in the column. Under these anaerobic conditions, anaerobic bacteria
like Clostridium predominate. These bacteria use the cellulose from the paper
to obtain glucose subunits. After obtaining glucose, the bacteria partially
break it down by fermentation, producing by-products like ethanol and organic
acids.

These by-products feed into other
bacteria. Desulfovibrio use the organic acids as a carbon source, they also use
the sulfate that was added to the column(desulfovibrio bacteria use sulfate as
a final electron receptor in respiration, producing hydrogen sulfide.).

The hydrogen sulfide is used by the
green sulphur bacteria and the purple sulphur bacteria, which will also use carbonic
dioxide obtained from calcium carbonate.

The presence of iron bacteria may explain
the orange coloured water. The black dots are probably desulfovibrio bacteria, the foul odour of the column is caused by them.
Finally, the brown colour can be explained by the presence of anaerobic
bacteria.